After a long delay, Federal Aviation Administration (FAA) approved battery system improvements for Boeing’s 787 Dreamliner on Friday. The manufacturer said the move clears the way for it and its customers to install the approved modifications and will lead to a return to service and resumption of new production deliveries.

“FAA approval clears the way for us and the airlines to begin the process of returning the 787 to flight with continued confidence in the safety and reliability of this game-changing new airplane,” said Jim McNerney, Boeing chairman, president and CEO. “The promise of the 787 and the benefits it provides to airlines and their passengers remain fully intact as we take this important step forward with our customers and program partners.”

Once the improvements are installed, 787s in the U.S. will return to service; for those aircraft based and modified outside the U.S., local regulatory authorities provide the final approval before the aircraft will fly again.

Approval of the improved 787 battery system was granted by the FAA after the agency conducted an extensive review of certification tests. The tests were designed to validate that individual components of the battery, as well as its integration with the charging system and a new enclosure, all performed as expected during normal operation and under failure conditions. Testing was conducted under the supervision of the FAA over a month-long period beginning in early March.

“The FAA set a high bar for our team and our solution,” McNerney said. “We appreciate the diligence, expertise and professionalism of the FAA’s technical team and the leadership of FAA Administrator Michael Huerta and Secretary of Transportation Ray LaHood throughout this process. Our shared commitment with global regulators and our customers to safe, efficient and reliable airplanes has helped make air travel the safest form of transportation in the world today.”

Boeing, in collaboration with its supplier partners and in support of the investigations of the National Transportation Safety Board and the Japan Transport Safety Board, conducted extensive engineering analysis and testing to develop a thorough understanding of the factors that could have caused the 787’s batteries to fail and overheat in two incidents last January. The team spent more than 100,000 hours developing test plans, building test rigs, conducting tests and analyzing the results to ensure the proposed solutions met all requirements.